meson: Make sink compile on Windows OS

We cannot compile app as a whole on MS Windows yet, but with those changes it is now possible to compile and run our new video sink alone on Windows OS

lib/gst/clapper/meson.build

@@ -43,6 +43,10 @@ if not gtk4_dep.version().version_compare('>=4.0.0')
   error('GTK4 version on this system is too old')
 endif
 
+if not gir.found()
+  error('Cannot build lib without GIR support')
+endif
+
 if gst_gl_have_window_x11 and (gst_gl_have_platform_egl or gst_gl_have_platform_glx)
   gtk_x11_dep = dependency('gtk4-x11', required: false)
   if gtk_x11_dep.found()
@@ -76,6 +80,18 @@ gstclapper_mpris_gdbus = gnome.gdbus_codegen('gstclapper-mpris-gdbus',
   namespace: 'GstClapperMpris'
 )
 
+gstclapper_deps = [
+  gtk4_dep, glib_dep, gio_dep,
+  gstbase_dep, gstvideo_dep, gstaudio_dep,
+  gsttag_dep, gstpbutils_dep, libm
+] + gtk_deps
+
+if os_unix
+  gstclapper_deps += giounix_dep
+else
+  gstclapper_deps += giowin_dep
+endif
+
 gstclapper = library('gstclapper-' + api_version,
   gstclapper_sources + gstclapper_mpris_gdbus,
   c_args: gstclapper_defines,
@@ -84,9 +100,7 @@ gstclapper = library('gstclapper-' + api_version,
   version: libversion,
   install: true,
   install_dir: pkglibdir,
-  dependencies: [gtk4_dep, glib_dep, gio_dep, giounix_dep,
+  dependencies: gstclapper_deps,
-    gstbase_dep, gstvideo_dep, gstaudio_dep,
-    gsttag_dep, gstpbutils_dep, libm] + gtk_deps,
 )
 
 clapper_gir = gnome.generate_gir(gstclapper,

lib/meson.build

@@ -9,6 +9,8 @@ cxx = meson.get_compiler('cpp')
 
 cdata = configuration_data()
 
+os_unix = host_machine.system() != 'windows'
+
 if cc.get_id() == 'msvc'
   msvc_args = [
     # Ignore several spurious warnings for things gstreamer does very commonly
@@ -243,7 +245,12 @@ libm = cc.find_library('m', required: false)
 glib_dep = dependency('glib-2.0', version: glib_req, fallback: ['glib', 'libglib_dep'])
 gmodule_dep = dependency('gmodule-2.0', fallback: ['glib', 'libgmodule_dep'])
 gio_dep = dependency('gio-2.0', fallback: ['glib', 'libgio_dep'])
-giounix_dep = dependency('gio-unix-2.0', version: glib_req, fallback: ['glib', 'libgiounix_dep'])
+
+if os_unix
+  giounix_dep = dependency('gio-unix-2.0', version: glib_req, fallback: ['glib', 'libgio_dep'])
+else
+  giowin_dep = dependency('gio-windows-2.0', version: glib_req, fallback : ['glib', 'libgio_dep'])
+endif
 
 cdata.set('DISABLE_ORC', 1)
 cdata.set('GST_ENABLE_EXTRA_CHECKS', get_option('devel-checks'))
@@ -251,7 +258,7 @@ cdata.set('GST_ENABLE_EXTRA_CHECKS', get_option('devel-checks'))
 configinc = include_directories('.')
 libsinc = include_directories('gst')
 
-gir = find_program('g-ir-scanner')
+gir = find_program('g-ir-scanner', required: false)
 gir_init_section = ['--add-init-section=extern void gst_init(gint*,gchar**);' + \
     'g_setenv("GST_REGISTRY_1.0", "@0@", TRUE);'.format(meson.current_build_dir() + '/gir_empty_registry.reg') + \
     'g_setenv("GST_PLUGIN_PATH_1_0", "", TRUE);' + \